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arXiv · 2307.07874

Beam Spin Asymmetry Measurements of Deeply Virtual $\pi^0$ Production with CLAS12

A. Kim·S. Diehl·K. Joo·V. Kubarovsky·P. Achenbach·Z. Akbar·J. S. Alvarado·Whitney R. Armstrong·H. Atac·H. Avakian·C. Ayerbe Gayoso·L. Barion·M. Battaglieri·I. Bedlinskiy·B. Benkel·A. Bianconi·A. S. Biselli·M. Bondi·F. Bossù·S. Boiarinov·K. T. Brinkmann·W. J. Briscoe·W. K. Brooks·S. Bueltmann·V. D. Burkert·R. Capobianco·D. S. Carman·J. C. Carvajal·A. Celentano·G. Charles·P. Chatagnon·V. Chesnokov·T. Chetry·G. Ciullo·B. Clary·G. Clash·P. L. Cole·M. Contalbrigo·G. Costantini·V. Crede·A. D'Angelo·N. Dashyan·R. DeVita·M. Defurne·A. Deur·C. Dilks·C. Djalali·R. Dupre·H. Egiyan·M. Ehrhart·A. ElAlaoui·L. ElFassi·S. Fegan·A. Filippi·C. Fogler·G. Gavalian·G. P. Gilfoyle·G. Gosta·F. X. Girod·D. I. Glazier·A. A. Golubenko·R. W. Gothe·L. Guo·K. Hafidi·H. Hakobyan·M. Hattawy·F. Hauenstein·T. B. Hayward·D. Heddle·A. Hobart·M. Holtrop·Yu-Chun Hung·Y. Ilieva·D. G. Ireland·E. Isupov·H. S. Jo·R. Johnston·S. Joosten·M. Khachatryan·A. Khanal·W. Kim·V. Klimenko·A. Kripko·S. E. Kuhn·L. Lanza·M. Leali·M. L. Kabir·S. Lee·P. Lenisa·X. Li·I . J . D. MacGregor·D. Marchand·V. Mascagna·B. McKinnon·D. Matamoros·S. Migliorati·T. Mineeva·M. Mirazita·V. Mokeev·P. Moran
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Abstract

The new experimental measurements of beam spin asymmetry were performed for the deeply virtual exclusive $\pi^0$ production in a wide kinematic region with the photon virtualities $Q^2$ up to 8 GeV$^2$ and the Bjorken scaling variable $x_B$ in the valence regime. The data were collected by the CEBAF Large Acceptance Spectrometer (CLAS12) at Jefferson Lab with longitudinally polarized 10.6 GeV electrons scattered on an unpolarized liquid-hydrogen target. Sizable asymmetry values indicate a substantial contribution from transverse virtual photon amplitudes to the polarized structure functions.The interpretation of these measurements in terms of the Generalized Parton Distributions (GPDs) demonstrates their sensitivity to the chiral-odd GPD $\bar E_T$, which contains information on quark transverse spin densities in unpolarized and polarized nucleons and provides access to the proton's transverse anomalous magnetic moment. Additionally, the data were compared to a theoretical model based on a Regge formalism that was extended to the high photon virtualities.

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A. Kim, S. Diehl, K. Joo, V. Kubarovsky, P. Achenbach, Z. Akbar, J. S. Alvarado, Whitney R. Armstrong, H. Atac, H. Avakian, C. Ayerbe Gayoso, L. Barion, M. Battaglieri, I. Bedlinskiy, B. Benkel, A. Bianconi, A. S. Biselli, M. Bondi, F. Bossù, S. Boiarinov, K. T. Brinkmann, W. J. Briscoe, W. K. Brooks, S. Bueltmann, V. D. Burkert, R. Capobianco, D. S. Carman, J. C. Carvajal, A. Celentano, G. Charles, P. Chatagnon, V. Chesnokov, T. Chetry, G. Ciullo, B. Clary, G. Clash, P. L. Cole, M. Contalbrigo, G. Costantini, V. Crede, A. D'Angelo, N. Dashyan, R. DeVita, M. Defurne, A. Deur, C. Dilks, C. Djalali, R. Dupre, H. Egiyan, M. Ehrhart, A. ElAlaoui, L. ElFassi, S. Fegan, A. Filippi, C. Fogler, G. Gavalian, G. P. Gilfoyle, G. Gosta, F. X. Girod, D. I. Glazier, A. A. Golubenko, R. W. Gothe, L. Guo, K. Hafidi, H. Hakobyan, M. Hattawy, F. Hauenstein, T. B. Hayward, D. Heddle, A. Hobart, M. Holtrop, Yu-Chun Hung, Y. Ilieva, D. G. Ireland, E. Isupov, H. S. Jo, R. Johnston, S. Joosten, M. Khachatryan, A. Khanal, W. Kim, V. Klimenko, A. Kripko, S. E. Kuhn, L. Lanza, M. Leali, M. L. Kabir, S. Lee, P. Lenisa, X. Li, I . J . D. MacGregor, D. Marchand, V. Mascagna, B. McKinnon, D. Matamoros, S. Migliorati, T. Mineeva, M. Mirazita, V. Mokeev, P. Moran. 2023-07-15. Beam Spin Asymmetry Measurements of Deeply Virtual $\pi^0$ Production with CLAS12. https://arxiv.org/abs/2307.07874

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